asks twice which disc it is if disc ID is ambiguous

If the disc ID is ambiguous, isrcsubmit asks twice which disc it is. It should probably remember the choice after the first time it has asked the question.

One such disc is Showbiz from Muse:
```
DiscID:         pTzIJonvMyKjLpu5iHjSX9FHPrU-
MCN/EAN:        0731454797924
Tracks on disc: 12

This Disc ID is ambiguous:
1: Muse - Showbiz (Official)
        AU      1999-10-04      9397603325724   MUSH332572
2: Muse - Showbiz (Official)
        GB      2003            5050466888624   5050466888624
3: Muse - Showbiz (Official)
        FR      1999-09-06      3298470521119   NV 3211-1
4: Muse - Showbiz (Official)
        US      1999-09-28                      0 9362-47382-2 0
5: Muse - Showbiz (Official)
        DE      1999-10-04      0731454797924   547 979-2
6: Muse - Showbiz (Official)
        GB      1999-10-04      5034644005928   MUSH59CD
Which one do you want? [1-6] 5


This Disc ID is ambiguous:
1: Muse - Showbiz (Official)
        AU      1999-10-04      9397603325724   MUSH332572
2: Muse - Showbiz (Official)
        GB      2003            5050466888624   5050466888624
3: Muse - Showbiz (Official)
        FR      1999-09-06      3298470521119   NV 3211-1
4: Muse - Showbiz (Official)
        US      1999-09-28                      0 9362-47382-2 0
5: Muse - Showbiz (Official)
        DE      1999-10-04      0731454797924   547 979-2
6: Muse - Showbiz (Official)
        GB      1999-10-04      5034644005928   MUSH59CD
Which one do you want? [1-6] 5
Artist:         Muse
Release:        Showbiz

found new ISRC for track 1: DEN129900317
found new ISRC for track 2: DEN129900318
found new ISRC for track 3: DEN129900319
found new ISRC for track 4: DEN129900320
ERROR: cdrdao gave the same ISRC for multiple tracks!
       ISRC: DEN129900321       tracks: 5, 6
found new ISRC for track 5: DEN129900321
found new ISRC for track 6: DEN129900321
found new ISRC for track 7: DEN129900322
found new ISRC for track 8: DEN129900324
found new ISRC for track 9: DEN129900325
found new ISRC for track 10: DEN129900326
found new ISRC for track 11: DEN129900314
found new ISRC for track 12: DEN129900327
```